Multi-functional catheter

ABSTRACT

A catheter suitable for delivering an electric current to the body, in particular a catheter having electrodes that can be positioned independently of the main elongate shaft of the catheter. More particularly the catheters include a movable sleeve that incorporates the electrodes. A movable sleeve includes one or more electrodes. Advances in the construction of the electrodes and related components are disclosed. Methods for positioning electrodes at a treatment site in the body for diagnostic or therapeutic applications, particularly electrical pharyngeal stimulation are also disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation U.S. application Ser. No. 14/009,195filed Nov. 13, 2013, which, in turn, is the U.S. national phase of PCTApplication No. PCT/GB2012/000288 filed on Mar. 30, 2012, which claimspriority to Great Britain Patent Application No. 1105622.3 filed on Apr.1, 2011, the disclosures of which are incorporated in their entirety byreference herein.

TECHNICAL FIELD

The present invention relates to novel catheters suitable for deliveringan electric current to the body, in particular to catheters that haveelectrodes that can be positioned independently of the main elongateshaft of the catheter. More particularly the invention relates tocatheters that include a movable sleeve that incorporates theelectrodes. It also relates to a movable sleeve that includes one ormore electrodes and to advances in the construction of the electrodesand related components. The invention also relates to methods forpositioning electrodes at a treatment site in the body for diagnostic ortherapeutic applications.

BACKGROUND

Catheters that include electrodes that are used for diagnosis, measuringand other medical applications are well known, catheters comprisingmultiple electrodes, for example, see U.S. Pat. No. 5,109,870 Silny.Whilst catheters comprising electrodes are known in the art, they sufferfrom a number of disadvantages.

International patent publication No. WO 2006/024825 (Hamdy) discloses acatheter for assisting recovery from dysphagia including a catheter forinsertion into the body of a patient via the mouth or nose, aparticularly useful application of the devices of the present invention.The electrodes are in the elongate shaft of the catheter such that whenthe catheter is in a suitable position within the patient's body, theelectrodes are in a position to apply electrical pharyngeal stimulation.

The present inventors have, however, found that accurate positioning ofthe catheter disclosed in Hamdy can be problematic. The catheter isrequired to fulfil two functions—firstly to safely and effectivelydeliver nutrition to the patients' stomach via an internal lumen of theelongate shaft of the catheter and secondly to deliver electricalstimulation to a defined region of the oropharynx via electrodes on theouter surface of elongate shaft of the catheter. The incorporation ofboth functions into the main body of the catheter has advantages, itminimize s patient discomfort and is consistent with existing standardsof care in that it replaces a conventional nasogastric (NG) feeding tubeand can be introduced into the patient in the same way as a conventionalNG tube.

The fixed position of the electrodes has, however, been found by theinventors to have some disadvantages. The catheter must be inserted intothe patient so that the distal end is correctly positioned in thestomach to meet the requirement to safely and effectively delivernutrition. The correct insertion distance can vary considerablydependent on the height of the patient and can routinely be different by20 cm or more from patient to patient. In contrast, the optimal positionfor the electrodes in the oropharynx is within a 2-3 cm verticaldistance range. Thus, in order to ensure that the electrodes on theelongate shaft of the catheter are correctly positioned there musteither be a range of catheter sizes to accommodate the variation inpatient height, or the catheter must be designed to be sufficiently longfor the tallest anticipated patient and then over inserted into shorterpatients in order to bring the electrodes into the correct position.This introduces risks that the distal end of the catheter does notremain in the stomach but continues into the duodenum, becomes entangledin the stomach preventing effective nutrition delivery or easy removal,or re-emerges from the stomach into the lower esophagus.

The fixed positioning of both electrical stimulation and nutritionfunctions in the invention of Hamdy et al. also has the disadvantagethat, in the event the internal lumen of the catheter becomes blockedwith nutritional feed in a way that cannot be resolved, the entirecatheter must be replaced.

In addition, it has become apparent that once the treatment withelectrical stimulation has been completed it may still be necessary tokeep the catheter in place solely for the purposes of enteral nutrition.This is not desirable from a patient comfort or safety managementperspective. It would be particularly advantageous for these reasons tobe able to remove the electrical stimulation functionality, whilstleaving the nutrition delivery functionality in place.

SUMMARY

The present inventors have now determined that a catheter that comprisesthe electrodes in a separate, movable electrode carrying componentprovides significant advantages to the accurate positioning ofelectrodes that are used to deliver electric current to the body. Thusthe present invention provides a catheter for delivering an electricalstimulus to the body comprising an elongate shaft; a sleeveincorporating one or more electrodes, the sleeve being movable along theelongate shaft such that the position of the sleeve is adjustable; and ameans to fix the sleeve to the elongate shaft once the sleeve is inposition.

Thus the present invention provides advantages over current catheterdesigns by permitting the incorporation of more than one function into asingle catheter and allowing each of the functions to be independentlypositioned and optimized. Thus the catheter comprises an elongate shaftthat may incorporate at least one therapeutic or diagnostic function.The catheter may thus comprise at least one diagnostic or therapeuticfunction in both the elongate shaft and the sleeve. The elongate shaftmay have a therapeutic function such as the provision of enteralnutrition, and the sleeve has electrical stimulation electrodes. Thecatheter may incorporate other diagnostic functions such as pressure orpH sensors.

The catheter of the present invention may also be configured such thatit allows for selective removal of certain functional components oncethey are no longer required, or in the event that their functionalitybecomes compromised. For example, the catheter can be configured suchthat the electrode carrying sleeve can remain in the body when theelongate shaft is removed.

It is also possible to configure the catheter such that the sleeve canbe removed leaving the elongate shaft in the body.

Examples of catheters according to the present invention thatincorporate more than one function include:

A catheter for electrical stimulation comprising a sleeve withelectrodes for the delivery of a stimulus and an elongate shaft withsensors to detect the effect of the stimulus delivered. Thus thecatheter combines an electrical stimulation function in the sleeve and adiagnostic function in the elongate shaft to measure the effect of thestimulus. Such a catheter may be configured such that the elongate shaftis movable.

This allows the effect of the stimulus to be assessed at a number ofdifferent positions without moving the point of stimulation.Alternatively the point of stimulation can be moved by moving thesleeve.

A catheter for the delivery of electrical stimulation comprising asleeve with one set of stimulating electrodes and an elongate shaft witha second set of stimulating electrodes. This would have the advantage ofallowing the distance between stimulation points to be adjusted asrequired but also keeping one stimulation point fixed if needed.

A catheter for measurement comprising a sleeve incorporating electrodeswherein the electrodes are sensors to measure for example pressure, EMGsignals or pH and a core elongate structure with sensors to measure forexample pressure, EMG signals or pH. This arrangement would provide thepossibility to measure the same parameters at a fixed and usercontrolled variable location simultaneously or measure two differentparameters at a fixed and user controlled variable locationsimultaneously. One example of a useful application using thisarrangement would be the measurement of lower esophageal sphincterstrength and separately the measurement of pH at multiple points alongthe esophagus.

A catheter for the delivery of electrical stimulation and themeasurement of pressure, comprising a sleeve that incorporates one ormore electrodes to deliver electrical stimulation, and an elongate shaftincorporating pressure sensors. The pressure sensors can be positionedon the elongate shaft such that they can be used to measure upperesophageal sphincter pressure. This arrangement would help to inform theuser whether the distal end of the catheter was in the upper airway orin the esophagus by virtue of pressure readings from the upperesophageal sphincter and facilitate the correct placement of stimulationelectrodes in the pharynx or esophagus rather than in the airways.

A catheter in the form of a two part catheter for the delivery ofelectrical stimulation and measurement of pH comprising a sleeve withelectrodes to deliver electrical stimulation and a core elongatestructure that was capable of extending as far as the patients' stomachand incorporating pH sensors at its distal end. This arrangement wouldhelp to inform the user whether the distal end of the catheter was inthe airways or in the esophagus by virtue of pH readings from thepatients' stomach and facilitate the correct Placement of stimulationelectrodes in the pharynx or esophagus rather than in the airways.

Another example would be a catheter for the delivery of electricalstimulation and nutrition, comprising a sleeve with electrodes todeliver electrical stimulation and an elongate shaft in the form of anasogastric feeding tube. This catheter could be used to treatdysphagia, particularly acute dysphagia, whilst also maintaining a safesupply of nutrition to the patients' stomach.

Thus the catheter of the present invention may be a pharyngealstimulation catheter for the treatment of acute or chronic dysphagia.

Dysphagia is the condition whereby a patient has difficulty inswallowing, or is unable to swallow. Dysphagia may be caused, forexample, by stroke, neurodegenerative diseases, and brain tumors or insome cases by other co-morbidity such as respiratory disorders.Dysphagia may be an acute condition arising due to acute neurologicaldamage following stroke or traumatic brain injury (TBI) and managed in ahospital setting. Dysphagia may also be a persistent or chroniccondition (defined as remaining present for periods greater than 6 weeksafter initial onset). This could be due to non-recovery from a stroke orTBI induced deficit, it could be a feature of a progressiveneurodegenerative disease such as Parkinson's disease or it could be afeature of a condition such as cerebral palsy or multiple sclerosis. Inthis case management is most often outside of a hospital setting.Dysphagia, whether acute or chronic, is a life threatening conditionprimarily due to the development of respiratory infections arising fromthe uncontrolled entry of food and liquids into the airways.

Dysphagia after stroke carries a six-fold increase of aspirationpneumonia by comparison with stroke patients without dysphagia.

It is envisaged that a pharyngeal stimulation catheter according to thepresent invention may have several, different configurations dependingwhether it is for the treatment of patients with an acute dysphagia orchronic dysphagia. For example where a patient is presenting withdysphagia post stroke in an acute care hospital environment it is likelythe patient will also require nutrition delivery via an enteral feedingtube. A configuration of the device to combine nutrition deliverycapability with the ability to also delivery therapeutic electricalstimulation to the pharynx is therefore particularly advantageous for anacute dysphagia patient. It is envisaged that this configuration of thecatheter for treatment of dysphagia and for nutrition delivery will usedin a hospital environment, will incorporate a feeding tube and be inplace for relatively long periods of time (up to 29 days). Analternative configuration particularly suited to treating patients withchronic dysphagia would not require the incorporation of an enteralfeeding tube but would have different functional requirements reflectingthe context of care i.e., potentially community based rather than in ahospital setting. The main function of the elongate shaft in this casewould be to facilitate placement of the electrode carrying sleeve at thetreatment site.

In the configurations where the elongate shaft is a nasogastric (NG)tube the elongate shaft may incorporate a visual position indicator onits external surface. The elongate shaft may also include connectorssuitable for engagement with an enteral feeding set.

However, as will be apparent to the skilled man, and as described above,it is envisaged that the catheters of the present invention, will beuseful in other therapeutic or diagnostic applications, particularlywhen it is desirable to adjust the position of the electrodes relativeto the position of the elongate shaft and or to accurately positionelectrodes at a treatment or diagnostic site.

Examples of the kind of functionality that may be incorporated into theelongate shaft or the sleeve of the catheter include but are not limitedto electrodes, sensors, transducers, wires, conducting materials, activechemical surface coatings, lubricants, balloons or stents.

The sleeve is dimensioned to permit it to move with respect to theelongate shaft. The sleeve may be dimensioned such that when thecatheter is in position in the body the sleeve extends to the outside ofthe body. This is advantageous as it permits the position of the sleeveto be adjusted from outside the body. It also means that the sleeve canbe positioned by the health care professional without the need for aseparate mechanism in the catheter to deploy or adjust the sleeve. Thusthe sleeve position can be adjusted manually.

Typically, the sleeve is a substantially transparent flexible tube madeof polyurethane, PVC, polyamide, silicone or equivalent material. Thesleeve is dimensioned to permit it to move with respect to the elongateshaft, thus it is sized to have a larger internal diameter than theexternal diameter of the elongate shaft. For example, if the elongateshaft is an adult nasogastric feeding tube, the dimensions of the sleevewill be approximately 5 mm in outer diameter, with an internal lumen ofapproximately 3 mm diameter and for approximately 35-45 cm in length.This arrangement is particularly suitable for a pharyngeal stimulationcatheter for the treatment of acute dysphagia. It will be apparent tothe skilled man that the dimensions of the sleeve may vary depending onthe patient population to be treated. For example, the feeding tube maybe 8F and the sleeve 14F.

The sleeve may incorporate one or more pairs of ring electrodes andconducting elements disposed laterally along the walls of the sleeveconnected to the electrodes. The walls of the sleeve may includepre-formed lumen for the conducting elements (wires). Thus the sleevemay be formed by multi-lumen extrusion. The sleeve may then beconstructed by inserting the wires into the appropriate lumen. The wiresmay be coated with an insulating material such as FEP (Fluorinatedethylene propylene) or the like.

The sleeve may also include a device, for example a Y connector, toguide the wires to an electrical connector.

The sleeve may be adapted to help it to slide over the elongate shaft.The sleeve and/or elongate shaft may be modified by coating with alubricant, by modification of surface hardness, by incorporation ofsurface features, or otherwise to allow free relative movement of sleevealong the length of the elongate shaft both whilst outside and insidethe patient.

The internal surface of the sleeve may be modified with respect to itshardness, shape, finish or coating such that the modification helps tominimize friction when the sleeve is placed or moved along the elongateshaft on which it is positioned.

The sleeve may have a position indicator, for example a visual indicatorsuch as printed guide or window on its surface to facilitate itspositioning relative to the elongate shaft.

It is possible to configure the catheter such that the sleeve can beremoved leaving the elongate shaft in the body. Such an arrangement isparticularly advantageous in the treatment of acute dysphagia, where theelongate shaft functions as a feeding tube.

A further feature of the invention is wherein the distal end of thesleeve is shaped to minimize patient discomfort. This shaping maycomprise a graduated or rounded end to ensure the sleeve does notdisturb the tissue during insertion or removal.

An important feature of the present invention is that the provision of aseparate sleeve and elongate shaft allows a single catheter to be usedwhere otherwise two or more might be required. In addition the presentinvention provides a catheter comprising movable sleeve and elongateshaft and a position indicator, the position indicator providing a meansto accurately position the catheter in the body.

Thus the catheter according to the invention may include a positionindicator arranged to indicate when the sleeve is correctly positionedon the elongate shaft. Typically the sleeve includes a positionindicator; however, it may be advantageous if both the sleeve and theelongate shaft include a position indicator. The catheter may comprise aposition indicator arranged to indicate when the sleeve is locatedcorrectly in respect of the elongate shaft and is thus in apredetermined position within a patient.

Position indicators according to the present invention may comprisevisible markings on an exterior surface of the sleeve and/or elongateshaft, such as a guide or scale on a surface of the sleeve to indicatevertical and/or lateral placement. The guide or scale may provide anumber of indicators depending on the patient to be treated, forexample, male or female and vertical distance ranges based on patientheight. Such guides or scales may be based on placement of the sleeve.In a preferred embodiment there is a printed window on the sleeve whichlines up with a printed guide on the elongate shaft identifying theinsertion distance. For example, in a pharyngeal stimulation catheterconfigured for acute use, the distance from the windows to theelectrodes will be in the range of 14 cm and 17 cm to ensure that theelectrodes will be in the correct position within the patient when thecatheter is inserted. The catheter may incorporate more than oneposition indicator, for example, more than one window which mayoptionally be color coded to cater for the different applications andsizes of patient or the route of catheter insertion (oral or nasal).

It will be apparent to one skilled in the art that the positionindicators may be combined with other catheter functions that providediagnostic information to facilitate correct placement of theelectrodes. For example a catheter for pharyngeal stimulation mayincorporate a position indicator in the form of a visual guide on thesleeve and/or elongate shaft and also a pressure sensor to detect thehigh pressure zone in the upper esophagus sphincter of the patient. Thepressure sensor may be incorporated into the sleeve or the elongateshaft of the catheter. Other suitable sensors include CO2, moisturecontent or pH sensors.

The catheters of the present invention have a sleeve that can moverelative to the elongate shaft, the catheter also having a means to fixthe sleeve in position. It may be advantageous if this fixing means isreversible. Thus after the sleeve is fixed in position on the elongateshaft it is still possible to release the fixing means to make furtheradjustments to the position of the sleeve and/or remove the sleeve orelongate shaft. The fixing means may be engaged before or afterinsertion into the patient. Advantageously, the fixing means is locatedat the proximal end of the sleeve.

The fixing means, for example in the form of a clip, may form part ofthe sleeve or be mounted thereon. The fixing means may be positioned atthe proximal end of the sleeve. However, particularly for a pharyngealstimulation application, the fixing means may be in the form of a clipthat is located externally of the body, i.e. at the proximal end of thesleeve/elongate shaft, when the catheter is in position in the body.Thus the catheter of the invention comprises a clip for fixing theposition of the sleeve relative to the elongate shaft, said clip beinglocated at the proximal end of the catheter.

Ideally the fixing means also functions to seal any gaps between thesleeve and elongate shaft, for example, when the clip is located at theproximal end of the sleeve, to prevent liquid or material ingressbetween the sleeve and the elongate shaft.

When not fixed in position the sleeve is capable of freely moving alongthe length of the elongate shaft. Advantageously, the fixing means maybe positioned at the proximal end of the sleeve and thus may remainaccessible to the operator when the catheter is inserted into the body.The fixing means, may form part of a Y-connector assembly and thereforepart of the sleeve if the sleeve incorporates a Y-connector. Forexample, the proximal end of the sleeve may be attached to a connector,which incorporates the fixing means, the fixing means acting on theelongate shaft, e.g. NG tube, to secure the position of the sleeverelative to the elongate shaft. This permits the user to move the shaftrelative to the sleeve and then engage the fixing means to secure thesleeve. The connector may also incorporate a conduit to guide the wiresto a suitable electrical connector. The connector may be in the form ofa Y-connector as discussed above. An example of such a connectorarrangement is shown in FIG. 5.

Alternatively, the fixing means may be a feature independent of butconnectable to a Y-connector.

The fixing means may take the form of a reversibly engageable clip fixedto the sleeve and capable of gripping the elongate shaft, for example byvirtue of ridges or equivalent on its inner surface. It may also operatein a similar fashion to a Touhy-Borst valve whereby a connector on thesleeve contains a deformable O-ring which can be reversibly compressed.In this way it is possible to hold or release the elongate shaft whichruns through the center of the O-ring. The reversibly engageable clip orfixing means may also take the form of a collet that grips the elongateshaft, or interference ribs or wave form that grip the shaft.

The fixing means may engage with the elongate shaft to fix the positionof the sleeve. The fixing means may include resiliently deformablematerials such as deformable silicone or the like. The fixing means maybe fabricated from this type of material, for example, in the form ofcompliant silicone grommet. Alternatively, the deformable material maybe used to coat the portions of the fixing means that engage with theelongate shaft, particularly if the elongate shaft is an NG feedingtube. If a deformable material such as a silicone or equivalent is usedit can have two useful features—it deforms to spread the applied loadand it creates friction such that the applied load can theoretically beless. These are both advantageous as a uniform loading and lower appliedpressure reduces the chance that the feeding tube gets deformed and thecross sectional area of the lumen is compromised (leading to increasedrisk of blockage).

Thus the fixing means, particularly a reversible fixing means, maycomprise a resiliently deformable material, for example a deformablesilicone or the like. The fixing means may be formed from or coated withthe resiliently deformable material.

Catheters according to the present invention may also include means forconnecting said electrodes to a power supply such as the wiringjunction, for example, in the form of a Y-connector or the like, asdescribed above. The means for connecting may be incorporated into thefixing means. In a catheter used for pharyngeal stimulation thisfacilitates removal of all of the electrical stimulus components uponremoval of the sleeve.

Thus the catheter according to the present invention may comprise anelongate shaft, a sleeve incorporating one or more electrodes, thesleeve being movable along the elongate shaft such that the position ofthe sleeve is adjustable; and a reversible means to fix the sleeve tothe elongate shaft once the sleeve is in position, the sleeve beingattached at its proximal end to a connecter and the connector includinga means for connecting the electrodes to a power supply and the meansfor fixing in the form of a reversible fixing means capable of grippingthe elongate shaft to fix the sleeve to the elongate shaft once thesleeve is in position.

The invention also provides advances in the incorporation of electrodesinto catheters by significantly improving the configuration of theelectrode components into a device for insertion to the body.

In a further aspect, the sleeve comprises multi-strand conductingelements extending along a length of the sleeve and terminating in atleast one electrode. Particularly the multi-strand conducting elementcomprises steel. More particularly, the conducting element is amulti-strand steel wire.

In the past, single stranded copper wire has been utilized in catheters,however, the inventors have discovered that copper wire can have anumber of significant disadvantages. Particularly, conventional copperwire is not robust enough at the appropriate diameter and when arrangedso that is attached to the surface of the sleeve may easily detach fromthe surface of the tube leading to puncture hazard. It also breaks moreeasily, leading to failure of the electrode. In addition, copper is moremalleable meaning that the wire exhibits differential stretching causingbunching or, again, wire detachment. However, insulated copper wire maybe used, particularly if inserted into a lumen in the wall of thesleeve. Thus the catheter according to the present invention maycomprise a sleeve with a wall incorporating molded lumen carrying wiresto the electrodes.

Multi-strand steel coiled wire is strong and more rigid with a reducedrisk of beading or bunching and breakage. Such wire adapts to thecurvature of the anatomy and negates the requirement for a separateguide wire. Surprisingly, when co-extruded, the adhesion between thesteel wire and the sleeve is stronger or greater than that of acomparable copper wire. Multi-strand wire means that each electrodecomprises more individual connections—if one wire fails, the electrodecontinues to function.

The inventors have identified a multiplicity of advantages in usingmulti-strand steel wire over more commonly used copper wires for theseapplications, specifically; The wires confer greater rigidity to thesleeve enhancing the process of catheter insertion.

Locating the wires on either side of the sleeve confers directionalconformity to the catheter (i.e., the sleeve will only easily bend inone plane) and therefore simplifies printing and use of surface guides.

The multi-strand steel wire is considerably stronger and forms a betterbond with the sleeve walls than copper. These features significantlyreduce the risk of wire breakage, leading to product fault or punctureinjury to the patient, and also prevent differential stretching of wireand sleeve walls leading to bunching or wire detachment.

This inventive concept therefore has application in either a novelsleeve according the present invention or may be incorporated into amore traditional catheter. In a further aspect of the present inventionthere is provided a catheter for delivering an electrical stimulus tothe body comprising a sleeve adapted to move over an elongate shaftwherein the sleeve comprises multi-strand conducting elements extendingalong a length of the sleeve and terminating in at least one electrode,the wire may be multi-strand steel wire.

In another independent aspect there is provided a catheter comprisingmulti-strand steel conducting elements extending along a length of thecatheter and terminating in at least one electrode.

The catheter as described above may be used for delivering an electricalstimulus to the body comprising applying electrical pulses capable ofinducing stimulation to electrodes located on the surface of an elongateshaft or sleeve, the catheter being inserted into the body of a patientand the electrodes being located in a position suitable for applyingelectrical stimulation to the target tissue or organ.

The catheter of the present invention has significant advantages overthe known devices and solves many of the problems associated with them.In particular the device is well adapted for the incorporation ofnasogastric feeding tubes.

Firstly it separates nutritional and stimulation functionality to allowboth to be positioned optimally on a per patient basis. This separationalso allows the nutrition component to be removed and replaced ifrequired (due to blockage) whilst retaining the stimulation componentlocated on the sleeve within the body. Leaving the sleeve in the body isadvantageous in that it facilitates replacement of the feeding tube byproviding a conduit or guide to aid introduction of the tube. Thisgreatly simplifies the procedure for replacing the tube as there isvirtually no risk of accidentally inserting the tube into the airways.It also means that the final position of the NG tube need not beconfirmed by X -ray. The presence of the sleeve also aids accuratevertical positioning of the replacement tube.

Separate nutritional and stimulation functionality also allows for thestimulation function, i.e. electrode carrying sleeve, to be removed fromthe patient on completion of electrical treatment, whilst the feedingtube remains in position in the patient.

One of the primary design challenges for a catheter intended to be usedto deliver an electrical stimulation inside the body is to identifymechanisms to safely and easily introduce the sleeve and in particularthe electrodes to the correct location in a manner most easily toleratedby the patient. Simple controls and confirmatory feedback should provideconfidence to users that the device has been safely and successfullypositioned. The device once placed should be secure, as comfortable aspossible and capable of supporting minor adjustments to maximizeelectrode contact in the correct location.

Nasal insertion has the advantage of avoiding some of the areas thatinduce a gagging response in patients.

Oral insertion has the advantage of allowing some direct visualizationof the path followed by the catheter and device and is consideredsomewhat less invasive. It is more subject to inducing a gag responseand more likely to result in unwanted movement of the catheter anddevice once it is placed.

International patent publication No WO 2006/024825 Hamdy discloses adevice for assisting recovery from dysphagia including a catheter forinsertion into the body of a patient via the mouth or nose. The cathetercomprises electrodes positioned such that when the catheter is in asuitable position within the patient's body, the electrodes are in aposition to apply electrical pharyngeal stimulation.

In a further aspect of the present invention there is provided acatheter as described above for use in delivering an electrical stimulusto the body to assist recovery from dysphagia. The catheter comprises asleeve adapted to move over an elongate shaft, one or more electrodesincorporated into said sleeve, means to fix the sleeve to said elongateshaft once in position and means for connecting said electrodes to apower supply.

When in use for this purpose the sleeve is positioned such that wheninserted into a patient the electrodes are in a suitable position forapplying electrical pharyngeal stimulation. In a further aspect thecatheter may comprise a means to facilitate correct positioning of theelectrodes in the form of a diagnostic sensor such as a pressure sensor.The sensor may be included in the sleeve or the elongate shaft. Thepressure sensor may be for the measurement of the high pressure zone inthe upper esophagus sphincter of the patient.

The catheter may comprise a means to confirm correct positioning of thecatheter and/or the electrodes in the form of a pH sensor. Ideally, thepH sensor is incorporated into the elongate shaft and may be used forthe measurement of stomach pH, thus the sensor may be at or near thedistal end of the elongate shaft. PH sensors such as those described inEP 2023881 may be particularly suitable for determining that the distalend of the elongate shaft (NG tube) of a pharyngeal stimulation catheteraccording to the present invention is located in the stomach.

Catheters incorporating a pressure sensor for measurement of the highpressure zone in the upper esophagus sphincter of the patient or a pHsensor are particularly useful for treating chronic dysphagia.

Ideally a pharyngeal stimulation catheter according to the presentinvention incorporates a position indicator and a sensor that providesdiagnostic information to facilitate correct positioning of theelectrodes.

A further aspect of the invention includes a method of assistingrecovery from dysphagia, comprising delivering an electrical stimulus tothe body comprising sliding a sleeve over the elongate shaft of acatheter, said sleeve comprising one or more electrodes, fixing thesleeve to said elongate shaft once in position, and delivering anelectrical stimulus to the body through said electrodes said electricalstimulus capable of inducing pharyngeal stimulation.

As will be apparent to the skilled man, the method may include slidingthe sleeve over the elongate shaft of the catheter, adjusting theposition of the sleeve and/or elongate shaft, fixing the sleeve to theelongate shaft and then inserting the catheter into the body. Theposition of the sleeve and/or shaft may, optionally, be further adjustedprior to delivering an electrical stimulus to the body.

Alternatively the sleeve is inserted into the body, followed by theelongate shaft, the position of the sleeve and/or shaft may, optionally,be adjusted after insertion.

In a preferred embodiment of the invention there is provided a method ofdelivering an electrical stimulus to the body comprising sliding asleeve over the elongate shaft of a catheter, said sleeve comprising oneor more electrodes, clipping the sleeve to said elongate shaft once inposition, inserting the device into the appropriate part of the body anddelivering an electrical stimulus through said electrodes.

The invention also provides a method of removing a slidable sleeve overa catheter, said sleeve comprising one or more electrodes and a means offixing said sleeve to said catheter, comprising unclipping the clippingmeans and sliding said sleeve over said catheter whilst leaving saidcatheter in situ.

Specific embodiments of the present invention will now be described, byway of example only, with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a single sleeve incorporating a connector, a clip and anelectrical supply connector, pair of electrodes, wires, a Y-connector, aclip and an electrical supply connector.

FIG. 2 shows a catheter comprising a sleeve as in FIG. 1 movablypositioned over a nasogastric feeding tube.

FIG. 3 shows a detail of the sleeve whereby a printed guide or window onthe surface of the sleeve can be aligned with marks or guides on thesurface of the core elongate structure on which the sleeve ispositioned.

FIGS. 4A and 4B show a catheter comprising a sleeve as in FIG. 1 movablypositioned over an elongate tube containing sensors for the measurementof physiological status or function

FIGS. 5 to 8 show various configurations of catheter comprising areversible fixing means incorporated into a connector.

FIG. 5 show a connector attached to the proximal end of the sleeve. Theconnector is in the form of a Y-connector that incorporates a reversiblefixing means in the form of a collet that grips the elongate shaft (NGtube).

FIG. 6 shows a Y-connector attached to the proximal end of the sleeve.The Y-connector incorporates a reversible fixing means in a wave formthat grips the elongate shaft (NG tube).

FIG. 7 shows a Y-connector attached to the proximal end of the sleeve.The Y-connector incorporates a reversible fixing means in the form ofinterference ribs that grip the elongate shaft (NG tube).

FIG. 8 shows a Y-connector attached to the proximal end of the sleeve.The Y-connector incorporates a reversible fixing means in the form of aclamshell case that engages with a slidable compliant grommet mounted onthe elongate shaft (NG tube).

DETAILED DESCRIPTION

A first particular preferred embodiment of the invention is for thedelivery of electrical pharyngeal stimulation to the oropharyngealregion for the treatment of acute dysphagia in combination with theability to safely deliver nutrition to the stomach. In this embodimentthe core structure (elongate shaft) is a nasogastric (NG) feeding tube,typically 8Fr in diameter and 125 cm or more in length, formed ofpolyurethane, PVC or silicone, radio-opaque, surface printed at 1 cmdistance intervals, terminating at the distal end in one or more feedingports and at the proximal end with connectors suitable for engagementwith an enteral feeding set. The sleeve is preferably a transparentflexible cover made of polyurethane or equivalent material, typically14Fr in diameter and 35-45 cm in length, incorporating a pair of ringelectrodes, wires connected to the electrodes for the delivery ofelectrical current and a Y-connector to guide the wires to a suitableelectrical connector. In addition the invention comprises a clip forfixing the position of the sleeve relative to the NG tube and a meansfor sealing the gap between sleeve and NG tube at the proximal end ofthe sleeve. When not fixed in position via the clip the sleeve iscapable of freely moving along the length of the core elongatestructure. The clip or seal may form a part of the Y-connector assemblyand therefore part of the sleeve or may be a feature independent of butconnectable to the Y-connector.

In this embodiment the connector at the proximal end of the NG tube maybe capable of being disconnected to allow the sleeve to be completelyremoved by sliding over the proximal end of the NG tube beforereplacement of the NG connector.

The connector could be configured for easy removal and reattachment tothe NG tube in a number of ways including a reversibly engageable clipcapable of gripping the NG tube, for example by virtue of ridges orequivalent on its inner surface. It could also operate in a similarfashion to a Touhy-Borst valve whereby NG connector contains adeformable O-ring which can be reversibly compressed through rotation ofa screw fit portion and in this way hold or release the tubing whichruns through the center of the O-ring.

The sleeve is a flexible elongate tube generally formed from a plasticmaterial such as polyurethane by a process of extrusion with distal (1a) and proximal 1 b) ends and with a bore (2) extending along itslength. The sleeve has a smooth or substantially circular outer surface(3) with at least one electrode, sensor or transducer disposed thereon.If the sleeve is used for the delivery of electrical stimulation, as inthe embodiment illustrated in FIGS. 1 and 2, generally there is at leastone pair of electrodes (4) positioned on the surface of the sleeve at alocation suitable for delivery of such stimulus to the patient. Theelectrodes are connected to two conducting elements (5) which aredisposed laterally within the walls of elongate tube and emerge from thewalls via small formed apertures into a Y-shaped junction (6) and fromthere via an insulated cover (7) to an electrical connector (8). Theconducting elements are preferably constructed from multi-strand wiresuch as steel multi-strand wire. A connection between the electrodes andconducting element (5) is made by removing a section of the sleeve toform apertures exposing the underlying conductive element. The wire maythen be bent back and a ring of conductive material applied usingconductive adhesive, melting or welding.

The sleeve has an aperture at both the distal (1 a) and proximal (1 b)ends in connection with the bore allowing the insertion of elongateshaft and the free movement of the sleeve along the length of the shaft.

As shown in FIG. 3 the sleeve has one or more guides or windows printedor otherwise marked on its surface (16) to allow it to be positioned ina controlled way relative to the core elongated structure (17) and withreference to marks or guides (18) printed on the surface of the coreelongate structure.

The sleeve is compatible with the use of a clip (19), which reversiblyfixes the sleeve to the core elongate structure once it has beenadjusted to the correct position relative to that structure. The clipmay be an integral part of the sleeve or may be a separate component. Inaddition to reversibly fixing the sleeve to the core structure the clipforms a seal to prevent ingress of liquids or particulate matter intothe space between sleeve and core structure.

A catheter according to the present invention, particularly such as thatshown in FIG. 2 is useful in a method for the treatment of acutedysphagia, such a method is described in detail below and involves:Measuring the insertion distance for the core NG tube component byplacing the distal end of the NG tube at the entrance to the patientnasal passageway, measuring the tube length to the earlobe and then tothe xyphisternum. The total distance figure being noted on the printedguide on the NG tube surface.

Disengaging the fixing clip on the sleeve if necessary and moving thesleeve along the surface of the NG tube until the appropriate window onthe surface of the transparent sleeve is lined up over the previouslynoted insertion distance number.

Engaging the fixing clip to prevent independent movement of the sleeveand introducing the catheter either orally or nasally but preferablynasally until the window over the correct insertion distance is justvisible at the entrance to the patients' nasal passageways.

Confirming that the distal end of the NG tube component is in thepatient stomach is via standard methods namely X-ray or aspiration ofstomach contents and testing of the pH.

Delivering nutrition via the core NG tube by connecting to conventionalenteral feeding apparatus.

Delivering therapeutic electrical stimulation by connecting anappropriate device to the electrical supply connector on the sleeve anddelivering the treatment via the electrodes in the sleeve.

Disengaging the fixing clip and adjustment of the sleeve without removalof the whole catheter assembly from the patient if required.

Disengaging the fixing clip and removal of the sleeve after thetreatment regime is finished but without removal of the NG tube.

Disengaging the fixing clip and adjustment of the sleeve without removalof the whole catheter assembly from the patient if required.

Disengaging the fixing clip and removal of the sleeve after thetreatment regime is finished but without removal of the NG tube.

Disengaging the fixing clip and removing the NG tube without removingthe sleeve from the patient if required and introduction of a new NGtube through the body of the sleeve until the correct insertion distancenumber is lined up with the window of the sleeve and engaging the fixingclip

In the first embodiment shown in FIG. 2 a catheter is described whichhas the dual functions of therapeutic electrical stimulation to treatacute dysphagia and delivery of enteral nutrition.

It comprises a core elongate structure in the form of a customnasogastric (NG) feeding tube (9) onto which is disposed a sleevecapable of freely moving along the length of the NG tube. The sleeve isa substantially transparent flexible tube made of polyurethane, PVC,polyamide, silicone or equivalent material, typically 4.7 mm in outerdiameter, with an internal lumen 3.3 mm diameter and 35-45 cm in length,incorporating a pair of ring electrodes, conducting elements disposedlaterally along the walls of the tube connected to the electrodes and aY-connector to guide the wires to an electrical connector. The internalsurface of the sleeve may be modified with respect to its hardness,shape, finish or coating such that the modification helps to minimizefriction when the sleeve is placed or moved along the NG tube on whichit is positioned. The sleeve has visual position indicator in the formof a printed guide or window on its surface to facilitate it'spositioning relative to the NG tube and is compatible with the use of afixing clip to secure the sleeve to the NG tube when required.

The NG tube is preferably 2.9 mm in diameter, with an internal lumen of1.9 mm in diameter, 125 cm in length, formed of polyurethane, siliconeor equivalent material with one or more ports (10) at its distal end(11) through which nutrients can be passed into the stomach. At itsproximal end (12) there is a connector (13) compatible with connectionto an enteral feeding set. This connector additionally has the capacityto be removed completely from the NG tube when required such that whenremoved the sleeve can be separated from the NG tube by sliding over theproximal end of the NG tube. The removable enteral connector can alsothen be replaced such that the device can continue to be used forenteral feeding purposes thereafter. The external surface of the NG tubemay be modified with respect to its hardness, shape, finish or coatingsuch that the modification helps to minimize friction between it and thesurface of the internal lumen of the sleeve. The NG tube has a guide incentimeters displaying the distance from the distal end printed on itssurface. The NG tube may also incorporate a guidewire (14) positionedwithin the internal lumen running from the proximal end of the NG tubeto a position 1-3 cm from the distal end of the NG tube and fixed to aconnector (15) compatible with the enteral connector.

The use of the device will now be described with reference to FIGS. 1and 2.

The distal end (11) of the NG tube is positioned adjacent to theexternal nostril of the patient. Whilst keeping the position of the endof the tube next to the nostril the tube is used to measure out thedistance to the patients' earlobe and then to their xyphisternum. Thetotal distance in centimeters from nostril to earlobe to xyphisternum(NEX) is obtained from the numerical printed guide on the surface of theNG tube. This represents the correct insertion distance for the NG tubeensuring that when the noted figure is visible at the entrance to thenostril sufficient tube has been inserted to allow the distal end to bewithin the stomach.

The sleeve is positioned on the NG tube by insertion of the distal end(11) of the NG tube into the proximal end (a) of the sleeve and pushingit through the bore of the sleeve until it emerges from the distal end(1 b) of the sleeve. The sleeve is moved along the surface of the NGtube until the printed window on the sleeve aligns with the insertiondistance figure on the printed guide on the NG tube. The sleeve is fixedto the NG tube using the clip on the Y-connector. This ensures that whenthe combined device is inserted nasally into the patient and the printedwindow is visible at the entrance to the nostril, sufficient tube hasbeen inserted both to allow the distal end of the NG tube to be withinthe stomach and to ensure that the electrodes on the sleeve are locatedwithin the stimulation target region in the oropharynx. The relativeposition of the sleeve on the NG tube may vary by 25 cm or more frompatient to patient.

The device is inserted nasally into the patient until the printed windowon the sleeve is visible at the entrance to the nostril. The guidewireis removed and the section of the device external to the patient securedin position. The correct position of the distal end of the NG tube inthe stomach is confirmed by pH testing of stomach aspirate or by X-ray.The enteral feeding connector (13) may be connected to an enteralfeeding set to allow nutrient delivery.

Therapeutic electrical stimulation is achieved by connecting anappropriate device to the electrical supply connector on the sleeve anddelivering the treatment via the electrodes in the sleeve. In the eventthat adequate contact between electrodes and target tissues cannot beobtained the clip (19) securing the sleeve to the NG tube may bedisengaged and small adjustments made to the vertical position of thesleeve before reengaging the clip. The patient will preferably receive10 minutes of stimulation at 75% of the maximum tolerated current levelat a frequency of 5 Hz and a pulse width of 2001JS for a period of 10minutes once per day for three consecutive days. In the event that theNG tube becomes irredeemably blocked the clip may be disengaged and theNG tube removed completely whilst keeping the sleeve in place. A new NGtube may then be inserted until the NEX figure is lined up in theprinted window of the sleeve and pH testing and X-ray carried out toconfirm presence of the distal end in the stomach.

Once the therapeutic electrical stimulation treatment regime is completeit may be desirable to remove the sleeve without removal of the NG tube.This is achieved as follows.

The NEX number on the surface of the NG tube visible through the printedwindow of the sleeve is noted. The clip securing the sleeve to the NGtube is disengaged and, holding the sleeve to prevent its movement,additional NG tube is inserted through the sleeve into the patient untila figure equal to NEX+20 cm appears in the printed window of the sleeve.The clip is then reengaged.

Both sleeve and NG tube are then slowly removed until the distal end ofsleeve emerges from the nostril and the original NEX number is visibleat the entrance to the nostril. This ensures that the distal end of theNG tube is still in the stomach.

If the patient is in the process of receiving enteral feed, the pump isswitched off and the enteral feeding connector disconnected from theenteral feeding set. The enteral feeding connector is then detached fromthe NG tube, the clip securing the sleeve to NG tube disengaged and thesleeve removed from the NG by sliding it over the proximal end of the NGtube. External parts of NG tube are wiped down with an appropriatedisinfectant wipe.

The enteral connector is re-attached to the proximal end of the NG tubeand then to the enteral feeding set such that feeding can be re-startedas required.

In a second embodiment shown in FIGS. 4 a and 4 b the device has thedual functions of electrical pharyngeal stimulation and measurement. Itcomprises a core elongate structure (9) onto which is disposed a sleevecapable of freely moving along the length of the catheter. The sleeve isa substantially transparent flexible tube made of polyurethane, PVC,polyamide, silicone or equivalent material, typically 4.7 mm in outerdiameter, with an internal lumen 3.3 mm diameter and 35-45 cm in length,incorporating a pair of ring electrodes, conducting elements disposedlaterally along the walls of the tube connected to the electrodes and aY-connector to guide the wires to an electrical connector. The internalsurface of the sleeve may be modified with respect to its hardness,shape, finish or coating such that the modification helps to minimizefriction when the sleeve is placed or moved along the catheter on whichit is positioned. The sleeve has a printed guide or window on itssurface to facilitate its positioning relative to the core elongatestructure. More than one window may be printed on the surface tofacilitate either nasal or oral insertion of the catheter. The sleeve iscompatible with the use of a fixing clip to secure the sleeve to thecore structure when required.

The core elongate structure (shaft) can take a number of forms. In oneembodiment (FIG. 4 a) it comprises a flexible tube typically 8Fr indiameter (20) and 50-70 cm in length, in a region near to its distal endsensors or other means to measure pressure (21) particularly pressureexerted by the action of the upper esophageal sphincter, within the bodyof the tube wires to connect to the pressure sensing means (22) and atits proximal end an electrical connector (23) to a suitable means forcapturing processing and displaying pressure data.

FIG. 5 shows a sleeve (24) having a connector in the form of aY-connector (25) that incorporates a reversible fixing means in the formof a collet that grips the elongate shaft (NG tube) (26) and alsofunctions to guide the wires (27) to a suitable electrical connector(28). The proximal end of the sleeve (24) is bonded into the proximalend of the Y-connector (29) by gluing, welding, over molding or thelike. The electrode wires (27) from the sleeve break out into a channel(30) in the connector to the electrical connector portion (28). AnEEPROM device may be incorporated in the connector. The reversiblefixing means comprises a two piece collet device (31) (32), comprising afirst piece (31) that can be adjusted by the user to grip or release theNG tube thus permitting the user to easily adjust the sleeve positionrelative to the NG tube position. The electrical connector portion ofthe Y-connector may incorporate a sealing mechanism e.g. cap (not shown)for infection control purposes, the cap is used to seal the electricalconnector when the electrical stimulation function is not in use.

FIG. 6 shows a Y-connector attached to the proximal end of the sleeve(24). The Y-connector incorporates a reversible fixing means in the formof a casing (33) that incorporates a “wave form” (34) that grips theelongate shaft (NG tube). The position of the sleeve relative to the NGtube is adjusted by the user and fixed by the user inserting the NG tubeinto the wave form channel (34) and closing the casing (not shown).

FIG. 7 shows a Y-connector (25) attached to the proximal end of thesleeve (24). The Y-connector incorporates a reversible fixing means inthe form of casing (33) having interference ribs (35) that engage theelongate shaft (NG tube) (26), the interference ribs create a labyrinththat locks the NG tube in place. The user may easily adjust the sleeveposition relative to the NG tube position and then fix the position byclosing the lid (36) of the casing.

FIG. 8 shows a Y-connector (25) attached to the proximal end of thesleeve (24). The Y-connector incorporates a reversible fixing means inthe form of a clamshell case (37) that engages with a slidable compliantgrommet (38) mounted on the elongate shaft (NG tube) (26). The grommetmay be made of suitable materials such as deformable silicone or thelike so that there is friction between the polyurethane NG tube and thegrommet.

The invention includes a method for the treatment of acute dysphagia,comprising;

-   -   Measuring the insertion distance for the core NG tube component        by placing the distal end of the NG tube at the entrance to the        patient nasal passageway, measuring the tube length to the        earlobe and then to the xyphisternum. The total distance figure        being noted on the printed guide on the NG tube surface.    -   Disengaging the fixing clip on the sleeve if necessary and        moving the sleeve along the surface of the NG tube until the        appropriate window on the surface of the transparent sleeve is        lined up over the previously noted insertion distance number.    -   Engaging the fixing clip to prevent independent movement of the        sleeve and introducing the catheter either orally or nasally but        preferably nasally until the window over the correct insertion        distance is just visible at the entrance to the patients' nasal        passageways.    -   Confirming that the distal end of the NG tube component is in        the patient stomach is via standard methods namely X-ray or        aspiration of stomach contents and testing of the pH. Delivering        nutrition via the core NG tube by connecting to conventional        enteral feeding apparatus. Delivering therapeutic electrical        stimulation by connecting an appropriate device to the        electrical supply connector on the sleeve and delivering the        treatment via the electrodes in the sleeve.    -   Disengaging the fixing clip and adjustment of the sleeve without        removal of the whole catheter assembly from the patient if        required.    -   Disengaging the fixing clip and removal of the sleeve after the        treatment regime is finished but without removal of the NG tube.    -   Disengaging the fixing clip and removing the NG tube without        removing the sleeve from the patient if required and        introduction of a new NG tube through the body of the sleeve        until the correct insertion distance number is lined up with the        window of the sleeve and engaging the fixing clip.

The use of this embodiment of the device will now be described withreference to FIGS. 1 and 4A.

The sleeve is positioned on the core elongate structure by insertion ofthe distal end (11) of the core structure into the proximal end (1 a) ofthe sleeve and pushing it through the bore of the sleeve until itemerges from the distal end (b) of the sleeve. The sleeve is moved alongthe surface of the core structure until the printed window on the sleevealigns either with a mark on the core structure corresponding to theaverage distance from the eternal entrance to the nostril to the centerof the upper esophageal sphincter or a mark corresponding to the averagedistance from the incisors to the center of the upper esophagealsphincter, depending on whether the device is to be inserted nasally ororally. The sleeve is fixed to the core structure using the clip on theY-connector. This ensures that when the combined device is insertednasally or orally into the patient and the printed window is visible atthe entrance to the nostril or incisors, sufficient tube has beeninserted both to allow one or more of the pressure sensors located indistal region of the core structure to be close to or within the upperesophageal sphincter whilst at the same time ensuring that theelectrodes on the sleeve are located within the stimulation targetregion in the oropharynx.

The electrical connector on the proximal end of the core structure (23)is connected to a suitable means for analyzing and displaying pressuremeasurements from the pressure sensors in the distal region of thecatheter. The combined sleeve and core structure are inserted eithernasally or orally until the printed window is approximately 5 cm fromthe entrance to the nostril or incisors. The means for displayingpressure measurements is then monitored whilst continuing to insert thedevice. A characteristic change in the pressure readings indicates thatthe pressure sensors are within the upper esophageal sphincter and thatthe distal end of the core structure is located within the esophagus andnot the upper airways. If required the device is further inserted untilsuch time as the printed window on the surface of the sleeve is locatedat the entrance to the nostril or incisors as appropriate. The part ofthe device external to the patient is secured in position to preventunwanted movement.

Therapeutic electrical stimulation is achieved by connecting anappropriate device to the electrical supply connector on the sleeve anddelivering the treatment via the electrodes in the sleeve. In the eventthat adequate contact between electrodes and target tissues cannot beobtained the clip (19) securing the sleeve to the core structure may bedisengaged and small adjustments made to the vertical position of thesleeve before reengaging the clip.

On completion of treatment the combined sleeve and core structure areremoved slowly from the patient. The clip securing the sleeve to thecore structure is disengaged and the sleeve removed by sliding it offthe distal end of the catheter. Subsequent treatments to complete thetreatment regime employ a new single use sterile sleeve each time. Thecore structure may be disposable or reusable. In the latter case thecore structure is sterilized between treatments by standard methodsknown in the art.

In the embodiment shown in FIG. 4B the core elongate structure comprisesa flexible tube typically 8Fr in diameter (39) and 125 cm in length, ina region near to its distal end sensors or other means to measure pH(40) particularly low pH values consistent with the distal end of theelongate structure being positioned within the stomach, within the bodyof the tube wires to connect to the pH sensing means (41), a guide incentimeters displaying the distance from the distal end printed on itssurface and at its proximal end a connector (42) to a suitable means forcapturing, processing and displaying pH data.

The use of this embodiment of the device will now be described withreference to FIGS. 1 and 4B.

The distal end of the core structure is positioned adjacent to theexternal nostril of the patient. Whilst keeping the position of the endnext to the nostril the core structure is used to measure out thedistance to the patients' earlobe and then to their xyphisternum. Thetotal distance in centimeters from nostril to earlobe to xyphisternum(NEX) is obtained from the numerical printed guide on the surface of thecore structure. This represents the correct insertion distance for thecore structure to ensure that when the noted figure is visible at theentrance to the nostril sufficient tube has been inserted to allow thedistal end to be within the stomach.

The sleeve is positioned on the core structure by insertion of thedistal end of the core structure into the proximal end (1 a) of thesleeve and pushing it through the bore of the sleeve until it emergesfrom the distal end (1 b) of the sleeve. The sleeve is moved along thesurface of the core structure until the appropriate printed window(depending on whether the catheter is to be inserted orally or nasally)on the sleeve aligns with the NEX number. The sleeve is fixed to thecatheter using the clip on the Y-connector. This ensures that when thecombined device is inserted nasally or orally into the patient and theprinted window is visible at the entrance to the nostril or incisors,sufficient tube has been inserted both to ensure the distal end of thecatheter will be in the patients' stomach whilst at the same timeensuring that the electrodes on the sleeve are located within thestimulation target region in the oropharynx.

The combined sleeve and catheter are inserted either nasally or orallyuntil the printed window positioned at the entrance to the nostril orincisors. The connector on the proximal end of the catheter (42) isconnected to a suitable means for analyzing and displaying pHmeasurements from the pH sensors in the distal region of the catheter. ApH reading of 5.5 or less is indicative that the distal end of the corestructure is located within the stomach and not the airways. The part ofthe device external to the patient is secured in position to preventunwanted movement.

Therapeutic electrical stimulation is achieved by connecting anappropriate device to the electrical supply connector on the sleeve anddelivering the treatment via the electrodes in the sleeve. In the eventthat adequate contact between electrodes and target tissues cannot beobtained the clip (43) securing the sleeve to the core structure may bedisengaged and small adjustments made to the vertical position of thesleeve before reengaging the clip,

On completion of treatment the combined sleeve and core structure areremoved slowly from the patient. The clip securing the sleeve to thecatheter is disengaged and the sleeve removed by sliding it off thedistal end of the core structure. Subsequent treatments to complete thetreatment regime employ a new single use sterile sleeve each time. Thecore structure may be disposable or reusable. In the latter case thecore structure is sterilized between treatments by standard methodsknown in the art.

What is claimed is:
 1. A catheter comprising: an elongate shaft; asleeve, the sleeve having a lumen there through for receiving the shaftand being movable along the elongate shaft such that position of theshaft is adjustable; and a clamp, wherein the clamp is movable betweenan open configuration, in which the position of the shaft is adjustablerelative to the sleeve, and a closed configuration, in which theposition of the shaft is fixed relative to the sleeve.
 2. A catheteraccording to claim 1, wherein the clamp comprises a first part and asecond part arranged in a hinged configuration.
 3. A catheter accordingto claim 2, wherein the clamp comprises a living hinge.
 4. A catheteraccording to claim 2, wherein the clamp is attached to the sleeve andeach of the first part and the second part of the clamp has an innersurface which, when the clamp is in the closed configuration, isengagable with the shaft to fix the position of the shaft relative tothe sleeve.
 5. A catheter according to claim 4, wherein one, or both, ofthe first and/or second part of the clamp comprises one or moreprojections for contacting the shaft when the clamp is in the closedconfiguration.
 6. A catheter according to claim 1, wherein the clamp isat least partially formed from a resiliently deformable material.
 7. Acatheter according to claim 1, wherein the clamp is integrated in aY-shaped connector.
 8. A catheter according to claim 1, wherein thesleeve incorporates one or more electrode.
 9. A catheter according toclaim 1 further comprising a grommet slideable on the shaft andengageable with the clamp.
 10. A catheter according to claim 9, whereinthe grommet is formed from a deformable material.
 11. An electricalconnector comprising a casing formed from a first part and a second partarranged in a hinged configuration and connection means for connectionto an electrical device, wherein the first and second part of the casingare movable between a closed position and an open position.
 12. Anelectrical connector according to claim 11, wherein the electricalconnector is a Y-shaped connector comprising three limbs and the casingand connection means are positioned on respective limbs of theelectrical connector.
 13. An elongated sleeve comprising: a lumen therethrough for receiving a cable or tube, and a clamp, wherein the clamp ismovable between an open position, in which the position of a cable ortube located in the sleeve is adjustable relative to the sleeve, and aclosed position, in which position of a cable or tube located in thesleeve is fixed relative to the sleeve.